This Program Project serves to draw attention to the problems and challenges of heart transplantation as an experimental system and to focus consideration of the potential efficacy of heart transplantation on a wider scale in the clinical arena. Special attention will be devoted to newer forms of immunosuppression in concert with monoclonal anti-T cell reagents. These will be most conveniently carried out in primates using a battery of antihuman T cell, hybridoma-produced reagents which engage various subsets of T cells. Additional immunosuppressives, such as Cyclosporin A, will also be used and in vitro monitoring of the proportions of T cell subsets will be carried out. Parallel pathological and physiological studies will be conducted.